1. Field of the Invention
The present invention relates generally to a component recovery process, and more specifically to a carpet recovery process that refines polypropylene backing polymer and nylon, polyester and polypropylene face fiber from whole carpet and rug edge trim.
2. Description of Related Art
The standard, whole carpet construction includes fiber tufts, backing, filler material and adhesive material. See FIG. 1. A standard construction of carpeting is illustrated schematically by reference numeral 1. The carpeting includes face yarn 2, tufted into a woven or spun bonded fabric 5 known as a primary backing. The primary backing 5 has pile yarns 2 tufted therethrough extending outwardly from one face, a primary backcoating or precoat 3 on the opposite face, and at least one secondary backcoating or main coat 4. Other layers may also be associated with the carpeting 1.
The primary backcoating or precoat 3 typically comprises latex, PVC (polyvinylchloride), EVA (ethylene vinyl acetate), or other polymer-based material, and the secondary backcoating 4 may also comprise or include polymers. Typically one or both of the primary backcoatings 3 and secondary backcoating(s) 4 include filler. The most common filler is mineral filler, typically calcium carbonate, although other fillers may be utilized, or calcium carbonate can be used with other common materials such as metal salts. Carpeting 1 may be produced with the filler of one or both of the primary backcoating 3 and secondary backcoating(s) 4 comprising waste carpeting instead of calcium carbonate as all or part of the filler.
The carpeting 1 may also have any number of other layers, depending upon use. For example, the carpeting 1 may have a conventional secondary backing (typically a woven or needle punched fabric adapted to contact the floor or padding).
In the usual mode of manufacturing carpet, the fiber tufts are tufted through a woven or non-woven fabric, which is the primary backing. The part of the tufts on the exposed surface of the carpet comprises face fiber. The latex-based adhesive is applied to the back of the tufted structure to lock in the tufts. Next, the woven secondary backing is attached to the back of the primary backing to give the carpet added dimensional stability, as well as to provide for additional tuft bind.
Usually, the very edges of the carpet have no fiber tufted through the primary backing or any latex adhesive applied for a width of typically about 1.75 to 4.5 inches. These edges are parallel to the machine direction of the carpet manufacturing process, and are used to guide the carpet through the machinery by means of tentor pins in the machinery, which pierce the edge of the carpet and hold it under tension.
As a final step in typical carpet manufacturing, and prior to rolling up the carpet for sale, these parallel edges, having served their purpose, are trimmed from the carpet, producing carpet selvage edge trim waste. Such edge trim waste is typically about 3 to 6 inches in width, and has a small portion of tufts, typically about 1.25 to 4.25 inches in width, at one edge.
Thus, the edge trim is primarily a narrow swath of the whole carpet structure with generally a higher weight percentage of the backing, typically polypropylene polymer, than does the whole carpet structure.
TABLE 1 illustrates a typical, standard construction of whole carpet by % composition of its component types.
TABLE 1% CompositionComponent Types40-60%Face fiber (including, among others, nylon 6, nylon 6,6,polypropylene, polyester, wool, cotton, acrylic, andcombinations there of) 8-20%Backing primary and secondary (most typicallypolypropylene)30-50%Filler material (most typically calcium carbonate)≦10%Adhesive material (most typically SBR latex rubber)
TABLE 2 illustrates a typical carpet selvage edge trim by % composition of its component types. As can be seen, the more expensive face fiber component is kept to a minimum on the edge trim.
TABLE 2% CompositionComponent Types≦60%Face fiber (including, among others, nylon 6, nylon 6,6,polypropylene, polyester, wool, cotton, acrylic, andcombinations there of)≧20%Backing primary and secondary (most typicallypolypropylene)≦40%Filler/adhesive residue (most typically calciumcarbonate - SBR latex rubber slurry)
As can be seen, whole carpet typically has less than a 20% composition of backing, while edge trim has a 20% or greater composition of backing.
Carpet selvage edge trim has historically been baled, and land filled as a postindustrial waste stream of the carpet manufacturing process. Recognizing the future value in this polymer rich edge trim scrap, the Dalton-Whitfield Regional Solid Waste Management Authority, Dalton, Ga., and possibly other landfills, have been isolating this material in “vaults”. Interest in these vaults of edge trim scrap is expected, as the value and availability of petroleum-based textile components increase. These vaults of stored edge trim, as well as that currently being generated by carpet manufacturing, will be a strategic source of raw material for recycling products. It is a key strategic cost savings for the assignee to capture this valuable edge trim internally, avoiding the landfill cost, and maximizing the value of the individual edge trim components by the present invention. Furthermore, it is the intention of this invention to mine these land-filled vaults of polymer raw materials as the maximum value of the individual components.
The land fill vaults of edge trim, as well as that generated by carpet manufacturing today, comprises a specific polymer face fiber (tufts) or combinations there of (see TABLE 2).
While edge trim can be segregated by face fiber type at the carpet plants, for example, as disclosed in U.S. Pat. No. 6,059,207, baled mixed face fiber edge trim is the typical carpet plant waste stream. The amount of face fiber pile left on the backing scrim is minimized by the carpet manufacturer. Therefore, compared to whole carpet construction, the edge trim almost always comprises a larger component concentration of backing polymer than that of whole carpet construction (see TABLE 1 and TABLE 2). This specifically points to a need in the art, wherein it would be advantageous to mix the backing rich edge trim selvage with face fiber rich post consumer as well as face fiber rich whole carpet post industrial scraps and trimmings.
Conventional recycling programs for the recovery of components of edge trim selvage involve utilizing the material “as-is”, or at a low percentage in a mixed low value composite product. Examples of such a product are mixed fiber padding and mixed polymer resin of limited application. Yet, whole edge trim value can be enhanced as a melt polymer with combinations of combatiblizers, modifiers, and other physical and chemical agents, used to enhance the whole edge trim composite melt mixture performance. Such agents most typically are quite costly, so their use is specifically and critically minimized compared to the weight percentage of the product.
Carpet selvage edge trim recycling is disclosed in U.S. Pat. No. 4,028,159, wherein selvage is heated to produce a mixture of meltable resins that is separated from any solid residue, and then used in the adhesive mixture in subsequent carpet manufacture. This melt filtration process produces recovered polymer that has been significantly degraded, adversely impacting the recovered polymers' physical properties. Finally, while the resulting mixed resin may be used in carpets with hot melt adhesive backings, as disclosed in applicant's U.S. Pat. No. 6,814,826, herein incorporated by reference, it is not desirable in a typical SBR latex-backed carpet, and the mixed resin has little value if sold on the waste market as a polymer.
U.S. Pat. No. 6,059,207 describes a carpet selvage waste polymer recovery process that first segregates edge trim by face fiber type, and then shears the desired polymer face fibers for highly purified recovery. This process is not being practiced, most probably due to its complexity (multiple intricate mechanisms, carpet mill cooperation and coordination of their variable processes), and the high cost of required multiple lines and locations for economic viability of face fiber recovery.
Therefore, it can be seen that a need yet exists for an effective edge trim component recovery process that efficiently and effectively separates and maximizes the value of the individual polymer and adhesive components. In addition to selvage recovery, it would be beneficial to provide a process that enhances the recovery of whole carpet post industrial scraps and pieces, as well as post consumer whole carpet scraps and pieces, as well as alloys or mixtures of selvage and whole carpet construction scraps and pieces. Furthermore, it would be beneficial to provide a process that can be utilized effectively with a feedstock of polypropylene face fiber whole carpet, as well as polypropylene face fiber selvage edge trim. It is to such processing that the present invention is primarily directed.